You can set up a hidden page and then "import" the content elements on a given page via typoscript on the pages (or the entire page tree below) as needed.
The "trick" is to use the colPos with the select-statement. With this you can even put multiple (different) content elements in one (hidden) page that show up on different pages (depending on the setting of the column they are "in".

Example:

Create a hidden (or system) page (here example-pageid = $PID_STATIC)

Create a content element on this page (text)

Edit this content element to be shown on the right column (right equals colPos=2)

Put the following typoscript into the template on which you want the content element to be shown. You can set the pid (pageId) in the constants via PID_STATIC or "hardcode" it into the typoscript.